Missing dead letter queue causes infinite retry resource exhaustion

Without dead letter queue configuration, permanently failed tasks exhaust retry limits and loop infinitely or consume resources attempting impossible tasks. Seen in initial Nexlify deployment with infinite retry loops.

Declare dead letter queue using broker.declare_queue('dlq', durable=True). Set max_retries=5 on actors. Configure Redis deduplication to prevent duplicate processing. Implement separate actor to handle DLQ messages for alerting and manual intervention.